Half-Life 2 is the continuation of the famous sci-fi action game Half Life. The game was developed for about five years, during which time several working versions of the project were "stolen" from the developers. However, these incidents did not affect the success of Half-Life 2.
Thanks to Half-Life 2, we learned about two phenomenal developments from Valve starting with the letter S — Source and Steam. The former is the game engine on which the game is built. It is not demanding on hardware, yet allows for very realistic physics, advanced AI for enemies, and stunning character animation. The latter is an online game distribution system, the most famous online game store in the world, and a favorite haunt for all PC owners. An interesting fact: Half-Life 2 was the first game to require online activation in Steam.
Half-Life 2 has become one of the most popular games of the past decade. The press awarded Valve's creation impressive positive reviews. By December 2008, over 6,500,000 copies of the game had been sold. Notably, more than a quarter of the total print run consisted of digital copies downloaded through Steam.